Extra filters are really not that expensive.My son has just started on a 125,and Ive got 4 filters for it.When both my sons raced yz 80´s I had 12 filters,I just pick up a couple of filters when I buy other parts.When we first started racing,I bought one of the filter cleaning sets with a bucket for cleaning fluid,and another for the oil.I just put the used filters in the cleaning fluid,untill its time to do filters again.I squeeze out the cleaner,rinse them inside out with hot water,and put them in the washing machine on a "soft" program,with ordinary washing powder! Lots of people think this is overkill,but try cleaning your filters like you use to,and put them in the washing machine inside an old pillow cover or something.The amount of sand particles inside the cover afterwards might make your hair stand up!
I put the clean filters on top of my central heater,and they are dry in a day or so.BTW,if you use the washing machine,be sure to wash your riding gear or work clothes at the next laundry,it can smell a little different than normal!
Hope Ive explained this in the right words,we dont normally speak English here.Ive done it this way for 10 years,countless hours of serious racing in all conditions,and not once have we blown engine parts because of particles entering the engine!